Preventing invasion of venomous fire ants

First detected in Japan this spring

防げるか毒アリの侵入拡大

  ―日本で初めて発見―

Image from Flickr.
Image from Flickr.

Fire ants, a poisonous species native of South America, have been discovered one after another across Japan, mainly in coastal areas, since late in May, causing grave concern among local residents. Once bitten by the insect, humans suffer a severe burning sensation and may die in extreme cases. While they have already been found in Australia, Taiwan, Southern China and some other Pacific Rim countries, their existence was confirmed for the first time in Japan. The Ministry of the Environment has been warning people to be on the alert. Is it possible to block their further invasion into Japan? And what precautions are being taken?

 刺されると猛烈に痛み、場合によっては死に至るという南米原産の猛毒アリ、ヒアリが5月末以降、沿岸部を中心に日本各地で続々と発見され、大きな不安を巻き起こしている。このアリはこれまでにオーストラリアや台湾、中国南部など環太平洋諸国で発見されているが、日本で確認されたのは初めて。環境省は注意を呼びかけているが、侵入の拡大を防ぐことはできるのだろうか。また、どのような対策が進められるのだろうか。

 

 According to the National Institute for Environmental Studies, fire ants vary in size from 2.5 to 6 mm, have a red brown body and darker abdomen, and build a nest (anthill) 15 to 50 cm tall on the ground. They are fierce and aggressive by nature, stinging humans over and over again. Their fertility is proved to be quite strong, with each queen producing up to 2,000 to 3,000 eggs per day.

 国立環境研究所によると、ヒアリは体長2.5~6ミリで、体色は赤褐色,腹部が暗色。地面に高さ15~50センチほどの巣(アリ塚)をつくる。性格は獰猛で、何度も刺す強い攻撃性を備えている。また、女王アリは1日に最大2000~3000個の卵を産むなど繁殖力が強いとされる。

 

 Japan’s Invasive Alien Species Act designates fire ants as a specific creature that disrupts the ecosystem and causes damage to agricultural, forestry and fishery industries as well as human life and health. Once a creature is so specified by the act, its feeding, cultivation, storage, transfer and import are placed under severe restrictions. Furthermore, the legislation requires the state and local governments to take preventive measures where necessary. Accordingly, effective countermeasures need to be urgently taken to prevent the insect from settling in Japan.

ヒアリは外来生物法で、生態系を損ね、人の生命・身体、農林水産業に被害を与えるおそれのある特定生物に指定されている。同法では、特定生物に指定されると、その飼養、栽培、保管、運搬、輸入などが規制され、必要に応じて国や自治体が防除を行うことを定めている。したがって、ヒアリが日本に定着しないよう駆除対策が求められている。

 

On July 4 when a swarm of fire ants were found at Osaka-Minami Port, then Environment Minister Koichi Yamamoto said at a press conference, “The government will do all it can to detect and exterminate (them) as early as possible,” stressing a policy to push ahead with what he called a shoreline operation across the country. In Kobe where fire ants were also detected on July 13, Mayor Kizo Hisamoto told his regular press briefing, “We will step up our fight against harmful alien species centering on insets by enlisting knowledge and information from experts.” The city has formed a task force, made up of Koichi Goka, head of the Ecological Risk Assessment and Control Section of the Center for Environmental Biology and Ecosystem Studies at the National Institute for Environmental Studies, and about 10 other members including specialists and Environment Ministry staffers, with a view to working out a basic plan geared for prevention at an early stage of the invasion by harmful alien species.

山本公一環境相は、大阪南港でヒアリが発見された7月4日、記者会見で、「早期の発見と駆除に全力を注ぐ」と、水際でのヒアリ駆除を進める方針を明らかにした。また、同じくヒアリが同13日に発見された神戸市は、久元喜造市長が定例会見で「専門家の知見を入れ、主に昆虫を中心に有害な外来生物への対応に力を入れていく」と述べた。同市では、国立環境研究所生物・生態系環境研究センターの五箇公一室長のほか、有識者や環境省職員ら10人前後構成する対策会議を開き、危険外来生物が侵入した際の初期対応など基本方針をまとめる予定。

 

Then, what have other countries done so far to counter the invasion by fire ants? On July 10, the Asahi Shimbun reported a successful case in New Zealand where fire ants were found in 2004 and 2006. It said that periodical checks in the port areas and citizens’ constant supply of relevant information resulted in an early detection of the insects, making New Zealand the sole country to exterminate them. Will Japan be able to keep quick-breeding fire ants at bay?

海外では、これまでどのような対策がなされてきたのだろうか。7月10日付け朝日新聞によると、2004年と06年にヒアリが発見されたニュージーランドでは、港周辺の定期的な調査や、一般人からの情報提供が早期発見につながり、唯一、根絶に成功したという。水際で止められるかが、大きな課題になりそうだ。

(Written by: Yuto Yawata)(八幡 侑斗)